Cathode support



Nov. 26, 1957 E. N. WYLER ET AL CATHODE SUPPORT 2 Sheets-Sheet 1 Filed Oct. 12, 1954 INVENTOR. EUGENE N. WYLER 'BY FRANCIS C. TODD ATTORNEY E. N/WYLER ETA Nov. 26, 1957 CATHODE SUPPORT 2 Sheets-Sheet 2 Filed Oct. 12, 1954 FIG.3

INVENTOR EUGENE N WYLER By vFRANGIS C. TODD ATTORNEY CATHODE SUPPORT Eugene N. Wyler, Worthington, and Francis C. Todd, Amlm, Ohio, assignors to the United States of America as represented by the Secretary of the Army Application October 12, 1954, Serial No. 461,946 1 Claim. (Cl. 313-478) The principal object of the present invention is to provide an improved cathode assembly for electron discharge tubes.

This invention relates to cathodes for electron discharge devices, and more particularly to cathodes for electron discharge devices of the magnetron type.

One object of this invention is to improve the cathode support in discharge devices and more specifically to allow for displacement of the cathode due to temperature changes.

Another object of the invention is to allow for thermal expansion of the cathode by supporting the cathode sleeve under compression.

The above and other objects and features of the invention will be made fully apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawings in which Figure 1 represents a sectional View of the cathode assembly constructed in accordance with the present invention and Figure 2 is a perspective view of an electron discharge device embodying features of this invention. Figure 3 is a sectional view of another embodiment of this invention.

Referring to Figures 1 and 2, the cathode assembly there shown comprises a cathode sleeve generally designated 15 supported at its ends by upper and lower supports 14 and 16. Upper cathode support 14 consists of a uniformly tapered heat radiating tube. The lower portion of the support 14 is recessed at 25 to receive and securely position the cathode 15. The cathode support 14 is mounted on support tube 12. The latter is aflixed to 24 as by puddle brazing. Centrally positioned in tube 12 is a two-part coaxial type terminal assembly 23 and 24. The upper and lower portions 24-11 of outer coaxial terminal assembly are divided and insulated by a glass insulating seal 13. The lower cathode support and heat radiator 16 is recessed at 26 to position and hold the lower portion of the cathode 15. Molybdenum powder is packed in the recesses at 25 and 26 between the cathode and the supports. Heat insulator 17 is interposed between spring 18 and support 16 to dissipate the heat so that the spring will remain cool enough to retain its elastic properties. To conduct the heater current across insulator 17, one or more electrical conductive strips 29 are attached to the lower end of rod 19 and support 16. Center rod 19 has the upper end 27 aflixed in the inner coaxial terminal assembly 23 while the lower end 28 is anchored under tension to the magnetron shell 20. Since the rod 19 carries the heater current from the inner coaxial terminal to the lower support of the ceramic-metallic heater, an insulating bead 30 is included to insulate the rod 19 from the shell 20. Spring 18 supplies the compressive force to the cathode 15 by urging the movable cathode support 16 toward the fixed support 14. The heater circuit extends from connector 23 through rod 19, metallic strip 29, support 16, cathode 15 to outer housing 14. This construction allows for thermal expansion of cathode while restricting lateral movement.

While the improved cathode sub-assembly can be employed in many types of magnetrons it is shown, for example, in conjunction with a multiresonant cavity type Patent magneton commonly known as the 4150 or 4152 magnetron. The magnetron, in Figure 2.. comprises an anode block 30 having a plurality of surrounding resonant cavities dimensioned to be resonant at the operating frequency. Anode block 30, provided with recesses 31 is sealed to blocks 32 and 33 to form an H section passageway. The flange member 24 of the cathode assembly is sealed hermetically to cylinder 34 which forms part of outer cylinder 37. Cylinder 37 is sealed to pole piece 35 at 38. The cathode 15 is positioned coaxially with the opening in anode block 30. Connection is established to the cathode by means of 23 and 24 which form a coaxial jack for receiving an appropriate plug. The interior of the tube is evacuated through exhaust tube 36.

Cathode 15 is held under compression at all temperatures by tungsten spring 18. The center rod 19, main tained under slight tension, permits thermal expansion of the cathode while rigidly holding the cathode centered in the anode structure. In this manner the difliculty formerly encountered by the shorting of the cathode and the anode elements is eliminated.

Referring to Figure 3, ceramic-metallic heater sleeve 55 is held in position by supports 53 and 59. Support 59 is spring biased by compression spring 52, attached to center rod 54, which compressibly supports cathode 58 between upper support 53 and lower support 59. Molybdenum powder is included at 58 in the cup shaped mounts between the heater sleeve and the supports. The rod 54 is aflixed to the lower support by means of a plug 56. Extension 57 of support 59 serves as a heat radiator. Leaf spring 52 is aflixed at the upper end to terminal assembly 60. Coaxial terminal assembly 5060 and cathode spindle 53 are used in the same manner as the corresponding elements in Figure 1. In this modification the spring is positioned at the top of the center rod away from the cathode which permits the spring to remain cool during operation.

In a specific case, the center rods are made of onesixteenth inch molybdenum rod. The tapered tubes and other parts which are close to the cathode are also made of molybdenum in order to conduct heat from the cathode. Metal parts located sufficiently distant from the cathode and not subjected to high temperatures are made from nickel and Kovar. When heat is dissipated from upper and lower supports of the cathode more uniform heat distribution is obtained over the emitting surface of the cathode. The resultant cathode assembly is rugged mechanically and has high heat dissipation.

While there has been shown the preferred embodiment of this invention, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the scope of the invention.

What is claimed is:

A cathode assembly for a magnetron comprising a cylindrical cathode, a coaxial connector having an inner and an outer contact member, means extending from said outer contact member for supporting one end of said cathode, a conducting rod having one end attached to said inner contact member and the other end to the magnetron frame, means for insulating said rod from said frame, a slidable support recessed to receive the other end of said cathode, spring means fixed at one end to said rod for urging said slidable support toward said cathode to support said cathode under compression, means for electrically connecting said rod to said slidable support.

References Cited in the file of this patent UNITED STATES PATENTS 2,269,081 Felsner Jan. 6, 1942 2,468,129 Spencer Apr. 26, 1949 2,477,601 Hanson Aug. 2.. 1949 2,518,121 Cahour et a1. Aug. 8, 1950 

